Method of and apparatus for surfacing refractory slabs or the like



United States Patent [72] Inventors Leopold l-I. Metzger Glencoe; Harold C. Miller, Chicago, Ill.

[2]] Appl. No. 731,591

[22] Filed May 23, 1968 [45] Patented Dec. 29, 1970 [73] Assignee Super-Cut,1nc.

Chicago, III. a corporation of Illinois Continuation-impart of application Ser. No. 521,135,.Iune 17, 1966, now abandoned.

[54] METHOD OF AND APPARATUS FOR SURFACING REFRACTORY SLABS OR THE LIKE Primary ExaminerHarold D. Whitehead Att0rneyNorman H. Gerlach ABSTRACT: A method and apparatus for surfacing slabs and removing high regions therefrom wherein kerfs are sawed through the high regions to produce intervening ribs or ridges which are then fractured to produce large segments which, after removal, leave only small protuberances that are erased by the abrasive action of a planar grinding surface. The fracturing and grinding are accomplished sequentially by a simple grinding head which rotates about a vertical axis and advances endwise along the ribs to fracture and thereby eradicate them. Tungsten carbide impact segments on the periphery of the head sweep laterally against the ribs in order to fracture them while grinding segments on the head wear away the protuberances left by the impact segments.

PATENTED 052291910 SHEET 1 [IF 3 INVENTORS LEOPOLD H. METZGER HAROLD C. MILLER ATT'Y PATENTED'nmawu SHEETE UF3 NOE PATENTEDDEEZQIQYU 3550.575

SHEET 3 UF 3 FIGB INVENTORS LEOPOLD H. METZGER HAROLD C. MILLER ATT'Y METHOD OF AND APPARATUS FOR SURFACING REFRACTORY SLABS OR THE LIKE This application is a continuation-in-part of copending US. Pat. application Ser. No. 52l,l35, filed by Leopold I-I. Metzger and Harold C. Miller on Jun. 17, 1966, now abandoned and entitled METHOD OF AND APPARATUS FOR SURFACING REFRACTORY SLABS OR THE LIKE.

The present invention relates to a novel method of and apparatus for surfacing refractory slabs and the like with a rapidity that has heretofore been unattainable when utilizing conventional slab surfacing methods and apparatuses.

It is obvious that in surfacinga concrete, marble, granite or similar refractory block or slabfor the purpose of reducing the faces thereof to a flat or planar condition, it is necessary by way of grinding to surface the slab on each face thereof to a depth which is no lessthan the depth of 'the lowest point thereon. This means that all of the refractory material which lies outside of the plane of such lowest point must be removed.

Where grinding operations are resorted to by utilizing a cylindrical or a planar abrasive grinding whe l or head, for each unit volume of material that-is removed om the slab, a proportional unit volume ofabrasive material on the grinding head is consumed. Considering a slab hailing a high region of large base area on a face thereof, the amount of refractory material which must be removed to reduce the face to a flat or ployed in connection with surfacing of the slab faces while, at the same time, reducing the faces to substantial flatness in a minimum length of time'The provision of such a method and apparatus constitutes the principal object of the invention and briefly, in carrying out this object, the invention contemplates as a first step or operation what may be considered a sawing operation whereby a multiplicity of closely spaced, relatively deep parallel kerfs are cut in the face of the refractory slab undergoing surfacing byway of a multiple blade saw, thus leaving a series of intervening-and spaced apart 'ribs which are by necessity of appreciable height. Thereafter, the ribs are fractured adjacent to their bases 'and thus broken away, leaving only a modicum of grinding to be performed before the face is reduced to a flat or planar condition;

The aforementioned'rnethod of rapid slab face reduction lends itself to a continuous operation, utilizing an apparatus whereby a rotary, power-driven multiple blade saw progressively saws the kerfs in the slab'face undergoing treatment and is followed by a rotary, power-driven, disc-type grinding head having mounted thereon certain impact segments which fracture and drive away by theforce of the impact the major portion of the ribs that are established by the multiple blade saw, and also having mountedv thereon other abrasive segments which operate to perform a cleaning-up or finishing operation by levelling the residual portions of the ribs.

This, in essence, constitutes the invention in its broadest aspect, but certain refinements have been developed to improve the efiiciency of the apparatus, one such refinement residing in the use of two or more rotary, multiple blade saws for establishing the kerfs in the face of the slab undergoing surfacing, the saws operating serially upon the slab face and the blades of one saw being staggered or laterally offset with respect to the blades of the other saw so that the blades of the trailing saw will create kerfs between the kerfs which are cut by the blades of the leading saw. By such an arrangement, not only is saw design and r'nounting simplified, but power input requirements for driving the saws are reduced to a minimum.

Another refinement which has improvedthe efficiency of the apparatus resides in the particular character of the impact LII segments which are mounted on the rotary grinding head, these segments being in the form of solid tungsten carbide blocks or hammers which sweep inwardly toward the ribs undergoing fracturing from the side thereof and near their bases. Each impact block, in addition to its impacting or hammering function, serves as a protectivefront for an abrasive grinding segment which lies directly behind or trails it and at an effective level slightly higher than the effective level of the aforementioned abrasive segments which perform the final cleaning-up or finishing operation.

In the accompanying three sheets of drawings forming a part of this specification, the invention has, to a large extent. been schematically illustrated.

In these drawings: 7

FIG. I is a top plan view, somewhat schematic in its representation, showing a slab surfacing apparatus that is capable of performing or carrying out the method of the present invention;

FIG. 2 is a side elevational view of the apparatus of F IG. 1;

FIG. 3 is a vertical transverse sectional view takenon the line 3-3 of FIG. 2;

FIG. 4 is an enlarged, quarter-section, side elevational view of one of the blades of one of the rotary, power-driven saws that are employed or utilized in connection with the present invention;

FIG. 5 is a vertical transverse sectional view taken substantially on the line 5-5 of FIG. 4;

FIG. 6 is a front elevational view of one of the rotary, power-driven grinding heads that are employed in connection with the invention for rib-fracturing and grinding purposes;

FIG. 7 is an enlarged transverse sectional view taken on the line "1-7 of FIG. 6; 5

FIG. 8 is a fragmentary side elevational view of the grinding head of FIG. 7; and

FIG. 9 is a schematic plan view of a slab face undergoing progressive treatment by the apparatus of the present invention and illustrating the method thereof.

Referring now to the drawings in detail and in particular to FIGS. I to 3, inclusive, a generally rectangular refractory slab 10 having opposite side faces 12 and 14 which are of an irregular or uneven nature and are to be reduced to a flat or planar condition, is centered and confined within a vertically extending, rectangular encompassing frame 16 having upper and lower longitudinal members 18 and 20 and end members 22 and 24. The slab 10 is maintained in its centered p sit'ion within the frame 16 by means of wedges 26 which are riven through inclined bores 28 in the upper longitudinal member 18 and operate to force the slab downwardly against a piurality of pads 30 on the upper side of lower frame memb r 20. The thickness of the slab 10, as shown in FIG. 3, is reater than the overall transverse dimension of the frame 16 so that the slab overhangs the frame on opposite sides thereof and presents its side faces 12 and 14 in an unobstructed rrjianner for surfacing.

The frame 16 is slidably supported on its lower longitudinal member 20 by way of a lower longitudinally extending supporting and guide rail 32, such rail being provided with an upwardly opening guide channel 34 of upwardly tapered design. Within the guide channel 34 there is slidably mounted a plurality of depending, downwardly tapered, friction shoes 36 on the underside of the lower frame member 20. The upper longitudinal member 18 of the frame 16 is guided in an upper, longitudinally extending guide rail 37 by a similar friction shoe and guide channel arrangement. The lower guide channel 34 is formed with a bottom extension 38 (see FIG. 3) in which It will be understood that the apparatus which is shown in the drawings is a fragmentary disclosure of a fully automatic apparatus wherein a succession of slabs, each carried in its respective frame, passes from a loading station where the slabs are applied to the frames, through the sawing station SS and the grinding station GS to an unloading station where the finished slabs are removed from their frames and the empty frames are then returned to the loading station.

The method of the present invention is practiced upon each slab as it passes successively through the sawing station SS and the grinding station GS. Means are provided at the sawing station for sawing in the opposite side faces 12 and 14 of each slab respective series of closely spaced kerfs 50 (see FIG. 8) which extend longitudinally of the slab and are separated by intervening ribs 52. The depth of these kerfs is a function of the character of the undulatory nature of the involved slab faces, the bottoms of all of the kerfs on each side of the slab being coplanar, with the maximum kerf depth being equal to the height of the highest crest on the undulatory involved side face. Kerf depth is, therefor, variable according to the displacement of material outwardly of the slab from the vertical plane of the low point of each side face undergoing treatment. As the thus created kerfs and ribs enter the grinding station GS, means are provided for fracturing the ribs 52 at the base regions thereof so that they will be forcibly removed from the slab. Thereafter, as the slab continues to progress through the grinding station, whatever trace of rib structure that may remain intact on the slab is then removed by a grinding operation so that the involved side slab face is brought to a smooth, flat or planar condition as indicated at 54 in FIG. 8.

In the exemplary form of apparatus for carrying out the method of the present invention, the kerfs 50 are sawed in the oppositely facing vertical side faces 12 and 14 of the slab by respective pairs of multiple blade saw assemblies 60, there being two such assemblies at the sawing station SS on each side of the path of travel of the slab 10. The four saw assemblies are identical, as are the paired arrangements thereof on opposite sides of the slab so that a description of one such arrangement will suffice for the other.

Each multiple blade saw assembly 60 is comprised of a series of spaced apart circular saw blades 62 and alternately arranged spacer collars 64 on a central drive shaft 66. The two drive shafts on each side of the slab 10 are operatively connected together for rotation in unison by any suitable means such, for example, as a belt and pulley arrangement 68. One of the two shafts 66 may be driven by a driving belt and pulley arrangement such as that which is fragmentarily shown at 70 and leads from a source of power (not shown).

While it is contemplated that a single saw assembly 60 may be provided at the sawing station for creating the kerfs 50 in the adjacent side surface of the slab 10, the required close spacing of saw blades to produce the closely spaced kerfs 50 would present problems of saw blade design, as well as require an undue power input. Therefore, in order to simplify the design of the assemblies 60 and to reduce the amount of power that is required to drive the same, two serially arranged assemblied 60 are provided on each side of the slab with the saw blades 62 of one assembly being staggered with respect to the saw blades of the other assembly in the transverse direction of the assemblies so that the leading assembly 60 (i.e., the assembly which first engages the adjacent side of the slab 10) establishes a first series (see FIG. 8) of kerfs having relatively wide spacing, while the second or trailing assembly 60 a establishes a second series of kerfs between the kerfs of the first series. On this basis, the kerfs 50 consisting of the two series are thus closely spaced, as are the intervening ribs 52.

The individual saw blades 62 of each saw assembly 60 are of conventional construction and each consists of a circular disclike steel blade body 70 (see FIGS. 4 and 5) to the periphery of which there is applied by a suitable brazing or soldering operation an annular series of circumferentially and equidistantly spaced abrasive segments 72. The segments 72 are of rectangular blocklikedesign and each comprises a sintered metal matrix throughout which there are uniformly distributed quantities of crushed or fragmented diamonds. The segments are arranged in end-to-end relationship on the periphery of each blade body 70 and the width thereof is slightly greater than the width of the blade body so that the segments overhang the side faces of the blade body as clearly shown in FIG. 5.

At the grinding station GS, a single grinding head is provided on each side of the slab 10. the two heads being identical. Each head 80 is carried on a drive shaft 82 and is driven by a suitable belt and pulley arrangement 84 leading from a common power input shaft 86.

The details of one of the grinding heads 80 are best illustrated in FIGS. 6, 7 and 8 ofthe drawings, each head including a generally cylindrical body 88, the forward peripheral edge of which is beveled. Two annular series of abrasive segments 92 are fixedly mounted on the inner planar end face 93 of the body 88. Such series are arranged concentrically and spaced a comparatively small distance apart and the segments 92 thereof are likewise spaced apart and preferably similar to the abrasive segments 72. An annular series of similar spaced apart abrasive segments 94 is fixedly mounted on the beveled edge 90. Another annular series of similar spaced apart abrasive segments 96 is fixedly mounted on the cylindrical outersurface 98 of the body 88. The various segments 92, 94 and 96 are of elongated rectangular design, the segments of each aforesaid annular series being disposed in end-to-end relationship.

As best illustrated in FIG. 8 and considering the head 80 to be oriented shown in this view with its axis extending vertically, each of the segments 96 is preceded by an impact member 100 in the form of an elongated rectangular block on tungsten carbide or other hard material having a high resistance to shattering upon impact. The various impact blocks 100 extend vertically in parallel side-by-side but spaced apart relationship and the upper region of the trailing side 102 of each block bears against the leading end face 104 of the associated or directly following segment 96, the medial and lower regions of the block projecting beneath the lower face 106 of said associated segment.

In the operation of the rotary grinding heads 80, the function of the impact blocks 100 and their trailing abrasive segments 96 is to cut arcuate swaths through the oncoming ribs on the side faces 12 and 14 of the slab 10, one arcuate swath being designated at 105 in FIG. 9. Considering each tungsten carbide impact block 100 and its associated abrasive segment 96 as a unit, the function of the annular series of units on the cylindrical outer surface of the body 88 of each head 80 is partially a chipping operation and partially an abrasive operation, large segments of the ribs 52 being variously fractured and broken from the ribs and thus forcibly ejected from the vicinity of the slab by the impacting force of the tungsten carbide impact blocks 100. The abrasive segments 96 which trail the impact blocks 100 as previously described initiate a preliminary grinding action on the portions of the ribs 52 which are not dislodged by the blocks 100, while further progressive grinding operations are performed by the abrasive segments 94, followed by a final smoothing operation under the influence of the abrasive segments 92. The segments 96 are largely abrasive in their function but they also have a minor impacting function of the tungsten carbide blocks 100. This minor impacting function of the segments 96 is related to the removal by impact of any small protuberances which may remain on the fractured portions of the ribs 52 after the tungsten carbide members 100 have passed thereagainst. Due to the minor nature of such impacting force of the segments 96, it is, in the same instance, not necessary to face such segments with blocklike tungsten carbide members.

As illustrated in FIG. 8, the upper end faces of the tungsten carbide blocks 100 and the upper side faces of the abrasive segments 96 are substantially coplanar and both lie in a common horizontal plane so that it would appear that, after the blocks have traversed a given rib 52, the segments 96 would sive, these segments serving to bring to a planar condition as indicated at 54 in FIG. 9-, any trace of rib structure which may remain after the rib regions of the slab 10 have moved inwardly toward the medial transverse planes of the grinding head. i

lt is to be noted from an inspection of FIG, 7 that the height of the units which are comprised of the impact blocks 100 and the segments 96 is less than the height} of the abrasive segments 94. Similarly, the height of the segments 94 is less than the height of the segments 92. By such an arrangement, continuity of removal of the material of the ribs is assured.

' The saw assemblies 60 and the grindi g heads 80 are capable of adjustment toward and away fro the slab 10 in order to establish different depths of cutting action by the former and different grinding planes by the latte As each slab passes successively through the sawing and rin ing stations, the

operator, by observing the character of the finished areas 54 of the slab, may control the depth of cut by the saw assemblies 60 and the spacing of the vertical planes of operation of the grinding heads 80 until all traces of rib structure disappear from the areas 54 on the slab.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification, the disclosure being largely schematic and representative of the basic principles involved in practicing the method of the present invention. Therefore, only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.

We claim:

l. The method of reducing an undulatory surface area on a refractory slab or the like to a substantially smooth planar condition, said surface area presenting relatively high and relatively low surface regions, said method comprising: progressively feeding the slab endwise through a sawing station and causing said surface to be operated upon at said station by a series of closely-spaced parallel saw blades which rotate in unison about an axis' parallel to the general plane of said undulatory surface in order thus to create a series of closely spaced narrow linearly straight kerfs through said high surface regions-with intervening ribs which are components of the original high surface regions, and continuing said endwise feeding of the slab through a second station and causing said ribs to move collectively and in endwise fashion against the periphery of a grinding head which rotates in a plane normal to said general plane so as to become fractured progressively along their leading ends by contact with a series of impact members disposed in the peripheral regions of said head so that relatively large rib fragments are dislodged from the ribs and forcibly ejected from-said surface, while simultaneously causing the surface from which said fragments are removed to traverse a planar abrasive end face on the rotatinghead and thus be reduced to planar configuration.

2. Apparatus. for reducing an undulatory surface area on a refractory slab or the like to a smooth planar condition, said surface areapresenting relatively high and relatively low surface regions, said apparatus comprising: an elongated conveyor for conducting the slab endwise in a longitudinal path,

means in the vicinity of said conveyor establishing a sawing station and a grinding station through which the slab on the conveyor is adapted to pass successively and in the order named, a gang saw disposed at the sawing station and positioned in the path of movement of the relatively high surface regions of said surface area of .the slab for progressively sawing a series of closely spaced parallel kerfs through said high sur'- rogresses through the sawing station,

face re ions as the slab I thus de imng a series 0 intervening llbS in said relatively high regions, and a grinding head disposed at the grinding station for rotation about an axis normal to the general plane of said surface area, said grinding. head presenting a substantially cylindrical periphery and a circular end face, a series of circumferentially spaced impact members mounted on said cylindrical periphery and eng'ageable with the base regions-of the oncoming ribs at the leading ends thereof for dislodging relatively large fragments from the ribs and ejecting them I from said surface area, and a series of abrasive segments mounted on said circular end face and engageable with the portions of the ribs from which said fragments hava been dislodged for finally reducing said surface area to a smooth planar condition. I

3. Apparatus as set forth in claim 2 including, additionally, a frustoconical area on said grinding head between said cylindrical periphery and said circular end face, and an annular series of spaced impact segments mounted on said frustoconical area and engageable with the leading ends of the oncoming ribs for rib-fracturing purposes. 

